Electrical heating device



June 5, 1934 F. J. HOLMES ELECTRICAL HEATING DEVICEv Filed Dec. '18, 192e Patented June 5, 1934 ELECTRICAL HEATING DEVICE Frank J. Holmes, Maplewood, N. J., assignor,`by mesne assignments, to Consolidated Electric Lamp Company, a corporation of Massachlsetts Application December 18, 1926, Serial` No. 155,694

Z Claims.

My invention relates to improvements in electrical heating devices and is more particularly directed to that type of device adapted for transmitting heat to an operating point or end, as in soldering, branding, surgical cautery instruments and the like.

The object of my invention is to provide a device wherein the heat producing element is so positioned with respect to the operative end that i.) heat imparted thereto by such element` is concentrated upon the operative end and largely prevented from being distributed to the shell or other parts of the device.

Another object of the present invention is to provide a device of the class described wherein the heat producing element is carried by a heat conducting member the end of which is made an integral part of the main casing to enable an effective hermetic seal to be obtained, but the shank of the member is spaced therefrom in such a manner that a heat insulating air space is provided between the member carrying the heat producing element and the walls of the casing.

Still another object of the invention is to provide a device having a main casing in which a heat producing element and its various parts are positioned and maintained therein in such a manner that movement of the heat producing element and its parts with respect to the heat conducting member and the casing is prevented.

Still another object of the present invention is to provide a handle for a tool of the class described wherein the tool is freely and adjustably supported within the handle and the free circulation of air between them is permitted.

Another object of the present invention is to provide a device of the class described having a main integral casing within which the various elements of the heating unit are placed and, when once in place, the casing is hermetically sealed to prevent the passage of air into or therefrom.

Another object of the present invention is to provide a device of the class described, having an improved construction and arrangement of connecting terminals.

Another object of the present invention is to provide a device of the class described having an increased durability of working surface. 50 These and other objects in view will be more fully apparent when the hereinafter contained description is taken in connection with the appended claims, and accompanying drawing, in whichz- Figure 1 is a longitudinal section View taken (Cl. 21S- 26) through the center of my improved tool and the handle carried thereby.

Figure 2 is a detail view of the heat conducting member which is integrally connected to and forms the end of the airtight casing of the tool.

Figure 3 is a detail view of the terminal plug and contacts carried thereby.

Figure 4 is a side elevation of the structure disclosed in Figure 3.

Figure 5 is a bottom plan View of the terminal plug with the contacts removed, showing the channels through which the leads pass.

Figure 6 illustrates a modified form of connecting the operative end with the heat conducting member of the tool.

Figures 'I and 9 illustrate modified forms of structure wherein the heat conducting member may be completely enclosed by the casing for a purpose hereinafter set forth; and

Fig. 8 illustrates a modified construction of the casing and heat conducting member whereby the taper of the brazed or welded joint between them is the reverse of the taper in Fig. 1.

Referring to the accompanying drawing in detail, wherein like reference characters denote corresponding parts throughout the several views, the numeral l indicates a cylindrical casing formed of a metallic tube, preferably steel, in which the'various elements of the heating unit are placed. It is of course to be understood that I do not limit myself to the specific shape of tube or casing herein illustrated, as it is my intention to change the size and shape of the casing either through a part of its length or throughout its entire portion, depending upon the size and capacity of the heating unit and the character of work upon which the tool is to be used.

As illustrated in Figure 1, one end of the casing 1 is internally reamed, as indicated at 2 to provide a beveled portion which forms a seat for a heat conducting member 3, having connected thereto in a manner hereinafter described, an operative tip 4.

' Upon referring to Figure 2 it will be noted that the member 3 is in the form of a cylindrical plug, formed of copper or other high heat conducting metal and having a tapered portion 5 which corresponds to the beveled seat 2 formed Within the casing 1. The heat conducting member 3 is further provided with a reduced portion 6 and a neck portion 7, as well as With an internal bore 8 which receives therein a suitable heat producing element 9.

In the assembly of the device, suitable uniting flux and brazing material is spread upon the en;-

gaging faces 5 of the heat conducting member 3 and 2 of the casing. after which the member 3 is inserted within the casing and united airtight thereto by heat. While I use this method of uniting the two parts, I may also accomplish the union by welding or the like. From the structure of the heat conducting member and the manner in which it is connected yto the casing it will be noted that by reason of the reduced portions 6 and 7 the member 3 is supported within the casing 1 only at its point of connection thereto at 2, thus forming an air space between the member and the casing and reducing greatly the amount of heat that would otherwise be conducted to the casing. 'Ihe member 3 has its exposed end portion provided with a threaded bore 37 in which is received one end of the soldering tip or the like 4, and upon referring to the drawing it will be noted that the bore 37 is separated from the bore 8 by a thin wall of metal, thus preventing the passage of air into the case while permitting the heat generated by the heat producing element to pass quickly to the tip. If desired. I may use in connection with a tool of this character any deaired tip or end and I do not of course limit myself to the specific type set forth.

'I'he heat producing element 9, which I have hereinabove referred to, is composed of a suitable insulating or insulated core 10 having wound thereabout a nlament 11, the ends of which are connected to leads l2 and 13 which unite the heating element with a source of current in a manner hereinafter set forth.

In this structure which I have just described, the heat producing element 9 is exteriorly wrapped with a covering composed of flexible sheets of mica, or other suitable insulating material as indicated at 14, the same having electrical insulating qualities, the purpose being to electrically insulate the heating element from the heat conducting member, and also to fill the space between the interior wall of the bore 8 and the heat producing element to frictionally retain the element rigidly within the heat conducting member and facilitate the conducting of heat to the walls of the member 3. After the heating element is thus wrapped it is inserted within the bore 8 of the member 3 and the leads therefrom extend rearwardly through the casing l.

I have inserted within the casing a mica disc or the like 15 of such a diameter that its frictional contact with the interior of the casing holds it immovably in place. 'Ihe mica disc is further provided with openings through which the leads 12 and 13 freely pass. After the leads are passed through the mica disc 15 it is then forced down within the interior of the casing 1 until it bears upon the end of the heat producing element 9, and thus it serves to maintain the heat producing element in place.

When the disc 15 has been inserted within the casing to its proper place a cylindrical insulating tube of lavite or the like 16 is then inserted within the casing, bearing upon the mica disc l5, the tube having therein passages 17 through which the leads 12 and 13 pass and are properly insulated from each other.

After the tube 16 has been properly placed, a disc 18 similar to the disk 15 is inserted within the casing 1, in a manner as hereinbefore set forth, and maintains the tube 16rin its place, as well as providing a support for the insulating material later placed within the open end of thecasingl. Themicadisclisofsucha diameter that it nts the interior of the casing so perfectly and it has therein small perforations which ilt the leads so tightly that the open end of the casing will hold liquid wax without its leaking through or around the disk 18.

When the disc 18 has been inserted within the casing 1 and moved to its proper position the leads l2 and 13'are then spaced apart to assume their intended positions with respect to each other, after which I pour within the open end of the casing 1 a suitable high melting point adherent insulating wax or the like 19 which iirmly adheres to the casing and to the wires, and seals the interior, thus preventing the free passage of air into and out of the casing. However, I have found that in some instances air has actually passed through the wax 19 and in order to prevent this I have sealed the end portion of the casing 1 by a second wax 20 having a greater degree of coherence and adhesiveness than the former.

After the waxes have been poured within the casing I then insert within the sealed end, while the waxes are hot, a pair of contact terminals 21 and 22, their adjacent end portions having formed therein openings or slots 23 of any desired shape and formation which the wax 19 will fill, thus firmly locking the contact terminals within the casing when the wax hardens.

Upon referring to Figures 3 and 4 it will be noted that the contact terminals 2l and 22 are each formed of a strip of suitable conductive metal being bent, as indicated at 24, and provided within the bend with a straight lug 25 which is formed by cutting its outline within the main part of the terminal and-then bending the main part down to leave the lug 25 protruding as illustrated in the drawing.

Before inserting the contact terminals within the wax they are each passed through a terminal plug 26 formed of suitable insulating material and having therein a passage 27 through which the legs of both terminals pass, and when thus inserted the ends of the lugs 25 will engage small shoulders 28 formed adjacent the passage so that the contact terminals rigidly hold the terminal plug in position, this being accomplished by reason of the fact that the lower ends of the contact terminals are locked with respect to the casing by the wax therein. Furthermore, while the lug of each contact terminal is engaging the shoulder 28 its main part abuts the edge of the passage 27 and in this manner maintains each contact terminal with respect to the other within the plug in such a manner that spreading or contracting of their adjacent ends is prevented.

Upon referring to Figure 3 it will be noted that the terminal plug 26 is provided with a vertical web 29, upon each side of which one of the ter minals 21 and 22 is placed, and as each contact terminal carries at its outer end a binding screw 30, the web is provided with opposite recesses or depressions 31 to receive therein the ends of the screws. 'Ihe contact terminals 2l and 22 have connected thereto, by the screws 30, lead wires 32 and 33 through which the device is connected to some suitable source of electrical supply.

The insulating plug 26 is further provided with diagonally arranged channels 34, as shown in Figure 5, formed within the walls of the passage 27, through which the leads 12 and 13 pass when the plug is inserted within the wax. These leads 12 and 13 are then bent at right angles, as indicated at 35, and then soldered to the contact terminals 2l and 22.

The contact terminals 21 and 22 are each further provided with a curved tip or hook 36 around which binding threads for holding the insulated leads 32 and 33 are wound, or, in the use of leads that are provided with strain relieving ties, the ties may be thus engaged with the projecting hooks, thusrelieving any strain upon the connection which may be imparted upon the leads.

In order to properly operate the tool I have provided a handle 38 which is formed of a cylindrical body having therein a bore 39, one end of which is reduced to provide an opening 40 through which the lead lines 32 and 33 pass, thus holding the lines centrally of the handle. To insulate the handle from the casing 1 in such a manner that in the event heat should be conducted to the 1 adjacent portion of the casing it will not affect the handle, I have provided within the bore of the handle a pair of spaced annular grooves 4l within each of which I have placed a coiled spring 42 which is composed of a number of coils the larger of which fit under tension within the grooves of the handle and the intermediate ones of which are of a smaller diameter than the others and than the casing 1, and by reason of the fact that the bore 39 is somewhat larger than the diameter of the casing 1, the springs 42 will slidably attach and support the easing of the tool freely within the handle. This structure permits the insertion and removal of the tool within the handle and in order that adjustability of the tool with respect to the handle may be effected I have positioned both springs adjacentone end of the handle and upon the end of the casing 1 I have provided a rib 43 which when the tool is withdrawn to its limit the rib will engage the innermost spring and thus prevent the accidental removal of the tool from the handle. Furthermore, in this structure by reason of the fact that the springs maintain the tool in a floating position within the handle, free circulation of air about the tool is permitted, thus obviating the possibility of the heat destroying the handle or rendering it uncomfortably hot.

Having thus fully described my invention I will now endeavor to explain more fully its mode of operation and use: Assuming that the work upon which this tool is desired to be used is of such a character that a short tool is desired, in such a case the tool is pushed within the handle until the insulating terminal plug abuts the reduced bore of the handle. If, on the other hand, a longer tool is desired, the tool is withdrawn from the handle to the desired length, the maximum length to which the tool can be extended being automatically indicated by the resistance of the lug or rib 43 when the innermost spring 42 hits against it. 'I'he leads 32 and 33 are then connected to some suitable source of supply and the current therefrom flows through the leads 32 and 33 to the contacts 2l and 22, through the leads 12 and 13 connected thereto and then to the heat producing element 9, from which the heat passes into the heat conducting member 3 and then to the soldering tip 4. By reason of the structure which I have set forth I am enabled to v provide a tool in which the parts thereof are reduced to a minimum and yet the result obtained is far superior to anything heretofore developed.

Upon referring to the modied forms disclosed in Figures 7, 8, and 9 it Will be noted that in each instance I have provided a similar heat conducting member 3 which is integrally connected to the operative end of casing l by any desired method. In Figure 7 the drawing illustrates what may be termed as a burning end and in this it will be noted that the end of the heat conducting member 3' is rounded and the steel casing 1 becomes a part of the end when bent therearound and integrally united thereto. This structure combines the operative end andlheat conducting member in one element.

In Figure 8 I have disclosed the same structure y as that broadly disclosed in Figure 1, but in this it will be apparent that the end of the heat,conducting member 3a tapers in the opposite direction, thus concentrating the heat to a smaller end and obviating the necessity of an enlarged end as,l on the heat conducting member 3.

` Figure 9 illustrates a heat conducting member 4b the end of which is tapered and the casing 1b is secured integrally thereto to form an operative end 4b.

From the foregoing, it is thought that the construction, operation and many advantages of the herein described invention will be apparent to those skilled in the art without further description, and it will be understood that various changes in the size, shape, proportion and minor details of construction may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention.

By the terms integrally united or integral therewith is meant united in such a way as by brazing, welding, or forming in a single piece of metal. F

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a heating device of the'class described, an outer casing which also forms the operative end of such device, a copper core integrally united to the inner surface of the operative end and separated throughout most of its remaining length from the casing, electrical heating element insulated from but carried by the copper core, terminals for connecting the device to the electrical supply leads, terminal wires for connecting the heating element to the said terminals and an adhesive wax for holding the terminals and terminal wires in place in the end of the casing.

2. In a heaing device of the class described, the combination of a casing having therein a heat producing element, an operative end, a heat conducting member connected to the casing and having integrally connected thereto the operative end, and a resilient wrapping about the heat producing element to retain the same within a bore formed inthe heat producing member.

3. In a heating device of the class described, the combination of a casing having therein a heat producing element, an operative end, a heat conducting member integrally connected to the casing and having a portion spaced therefrom,

said conducting member receiving therein the heat producing element, and a resilient wrapping about said heat producing element to insulate the same from the heat conducting member and f the heating element from the other end oi' the casing.

5. In a heating device of the class described, the combination o! an outer casing, a heat conducting member received within said easing, said member and casing I having complementary tapered engaging portions near the working end o! the device. said portions being integrally united to form an airtight seal and means to prevent access of air to the interior of the casing.

6. In a heating device oi the class described, a casing having therein a heat producing element near its working end, an insulating terminal connection plug located at the opposite end of the casing, means for providing electrical connection between said terminal plug and said heat producing element and an insulating compound within said casing adjacent said terminal plug, said terminal plug having one or more parts projecting therefrom and embedded in said compound to hold the terminal plug in place.

7. In a heating device o! the class described, a casing having therein a heat producing element near its working end, an insulating terminal connection plug located at the opposite endl of the casing. said terminal plug having contact terminais projecting into said casing, conducting leads extending from said heat producing element and elec'rically connected to said contact terminals, and an insulating compound within said casing in which the said terminals are embedded to hold the terminal plug in place.

8. In a heating device of the class described, the combination of a casing having therein a heat producing element, a handle member surrounding said casing and springs adjustable to different positions longiudinally of the casing for holding said handle member in desired position thereon.

9. In a heating device of the class described, the combination oi' a casing having therein a heat producing element, a handle member surrounding said casing and one or more coiled springs interposed between said handle member and said casing having turns oi different size respectively engaging the handle member and casing to hold the handle member in place and in spaced relation to the casing.

l0. In a device of the class described, the combination o! an inner member subjected to heat durim use, a handle member surrounding said inner member and a spring support for said handle member interposed between the same and said inner member to hold the handle member in place and in spaced relaion to said inner member.

1.1. In a heating device of the class described, the combination of a metallic casing having therein a heat producing element, an operative end, an elongated heat conducting member of a size to ilt within the casing with the majority oi its length spaced from the casing and a small part of its length integrally united to the casing, said heat conducting member having a bore to receive the heat producing element and means to prevent access of air to the interior oi the casing.

l2, In a heating device of the class described,

`oi' its length integrally united to the casing near said operative end, said'heat conducting member having a bore to receive the heat producing element and means to seal the other end ot the casing to prevent access of air.

13. In a heating device of the class described, the combination ot an exterior casing, a heat conducting member within the casing, a heat producing element within the heat conducting member, said heat producing element including an insulated core having a recess, a resistance wire wound on the core, a. lead wire fastened to the resistance wire to form an electrically conductive connection, the said connection lying in the said recess in the core.

14. In a heating device of the class described, the combination of an exterior casing, a heat conducting member within the casing, a heat producing element within the heat conducting member, said heat producing element including an insulated core having a recess across one end, a resistance wire wound on the core, a lead wire fastened to the resistance wire to form an electrically conductive connection, the said connection lying in the said recess in the core.

15. In a heating device of the class described, the combination of a casing, a heat producing element within the casing near the operative end thereof, relatively heavy lead wires extending from the heat producing element toward the handle end of the casing, an insulating tube smaller than the interior of the casing having two spaced passages therethrough for the lead wires and extending from a point near the heat producing element toward the handle end of the casing. and a disc of insulating material having openings for the lead wires situated within the casing between the heat producing element and the insulating tube, the edges of the disc irictionally engaging the casing and the openings therein being so spaced that the lead wires assist in supporting the insulating tube out of contact with the casing.

16. In a heatingdevice of the class described, a casing having therein a heat producing element near its working end. an insulating terminal connection plug located at the opposite end oi' the casing, said terminal plug having a, shoulder to engage the end of the casing and contact terminals projecting into said casing, conducting leads extending from said heat producing element and electrically connected to said contact terminals and an insulating compound within said casing in which the said terminals are embedded to hold the terminal plug in place.

l?. In a heating device of the class described, a casing having therein a heat producing element near its working end, an insulating terminal connection plug located at the opposite end of the casing, said terminal plug having contact terminals projecting into the casing, cooperative engaging means on the plug and on the terminals to prevent the terminals from passing entirely through the plug, conducting leads extending from said heat producing element and electrically connected to said contact terminals, and an insulating compound within said casing in which the said terminals are embedded to hold the terminal plug in place.

18. In a heating device of the class described, a casing having therein a heat producing element near its working end, an insulating terminal connection plug located at the opposite end of the casing, said terminal plug having contact terminals projecting into said casing, conducting leads extending from said heat producing element and electrically connected to said contact terminals, and an insulating compound which is impervious to air filling the end oi the casing and within which the said terminals are embedded to hold the terminal in place and render air-tight the end of the casing.

19. In a heating device of the class described, a casing having therein a heat producing element near its working end, an insulating terminal connection plug located at the opposite end of the casing, said terminal plug having contact terminals projecting into said casing, conducting leads extending from said heat producing element and electrically connected to said contact terminals, and Van insulating compound which is impervious to air filling the end of the casing and within which the said terminals and a part of the terminal plug are embedded to hold the terminal plug in place.

20. In a heating device of the class described,

FRANK J. HOLMES.

CERTIFICATE OF CORRECTION.

Patent No. 1, 961, 496.

FRANK J.

June 5, 1934.

HOLMES.

lt is hereby certified that error appears in the printed specification of the above numbered patent. requiring correction as follows: Page 3,

2, strike out the word line 127, claim integrally" and insert the same before "connected" m line 126; and line 130, same claim, for "producing" that the said Letters Patent should be read with th the same may conform to the record of the case in read conducting; and ese corrections therein that the Patent Office.

Signed and sealed this,24t`h day of July, A. D. 1934.

Bryan M. Battey Acting Commissioner of Patents. 

